Register Map for the PCI-PDISO16

Transcription

1 Register Map for the PCI-PDISO16 Document Revision 1, September, 2003 Copyright 2003, Measurement Computing Corporation

2 PCI-PDISO16 Register Description Register overview PCI-PDISO16 registers are mapped into I/O address space. Unlike ISA bus designs, this board has several base addresses that correspond to a reserved block of addresses in I/O space. Of the six base address regions (BADR) that are available in the industry standard PCI 2.1 specification, two are implemented in this design and are summarized as follows: I/O Region Function Operations BADR0 PCI Controller Operation Registers 32-Bit DWORD BADR1 General Control/Status Registers 8-Bit BYTE BADRn is likely different on different machines. Assigned by the PCI BIOS, these base address values may not be the same even on subsequent power-on cycles of the same machine. All software must examine BADR0 at run-time with a READ_CONFIGURATION_WORD instruction to determine the BADRn values. BADR0 address mapping BADR0 is reserved for the AMCC S5933 PCI Controller operations. PCI-PDISO16 users need not access this region of I/O space. This region supports 32-bit DWORD operations. For more information, refer to Applied Micro Circuits Corporation's (AMCC ) PCI Products Data Book (April, 1998) available at BADR1 address mapping Two 8-bit registers are written to control the 16 relays, two 8-bit registers are read to monitor the 16 digital inputs, and two 8-bit registers are written to enable/disable the low pass filters on the inputs. The board is configured as two independent 8-bit I/O ports. Each of the 8-bit ports uses distinct I/O addresses and connectors. For descriptive purposes they are called I/O Port A and I/O Port B. The overall address/register map is shown below. Connector locations are shown in Figure 1. Port A: BADR1 + 0 Relay Output Read/Write BADR1 + 1 Isolated Inputs Read Only BADR1 + 2 Filter Control Write Only BADR1 + 3 Not Used Port B: BADR1 + 4 Relay Output Read/Write BADR1 + 5 Isolated Inputs Read Only BADR1 + 6 Filter Control Write Only BADR1 + 7 Not Used Although the PCI-PDISO16 decodes eight addresses, only six are used. 1

3 Register Map for the PCI-PDISO16 Figure 1. PCI-PDISO16 Port Locations The registers are written to and read from as single 8-bit bytes. Each bit controls an output or represents the state of a device or input. Registers are read left to right, with the leftmost bit being the most significant bit. Following this format, bit 7 of BADR+0 corresponds to relay 7, and bit 0 corresponds to relay 0. To assemble a control word, use the following table to determine bit weight: For example, to assemble a control byte to turn ON relays 0, 1, 3, 5 and 7: RELAY HEX ON=1 WEIGHT DECIMAL ON=1 WEIGHT RELAY RELAY RELAY RELAY RELAY RELAY RELAY RELAY AB 171 The isolated inputs are read in this format as well. To disassemble the byte and determine the state of the isolated inputs or the relay read back register, perform the following operation in software: INPUT/RELAY HEX DECIMAL INPUT 7 / RELAY INPUT 6 / RELAY INPUT 5 / RELAY INPUT 4 / RELAY INPUT 3 / RELAY INPUT 2 / RELAY INPUT 1 / RELAY INPUT 0 / RELAY Perform an AND operation for each bit to see if it is ON. In the following example, the variable INPBYTE% is the isolated input byte read from BADR + 1. This example is in Microsoft Basic, though the logic used is easily translated to any language. INPBYTE% = INP(BADR + 1) INP7% = INPBYTE% AND &H80 IF INP7% <> 0 THEN ISOINP$ = "ON" ELSE ISOINP$ = "OFF" When this code executes, it determines the state of a particular input. This type of logical bit testing is required to check inputs independently. 2

4 Register Map for the PCI-PDISO16 Relay output registers The relay output registers are located at BADR1 + 0 (Port A) and BADR1 + 4 (Port B). WRITE READ CONTROL Write a byte to the register to control the relays. A 1 in the relay bit position turns the relay ON. STATUS Read the status of the relay control register. A 1 in the relay bit position indicates the relay is ON. ON indicates that the relay common is in contact with the normally-open (NO) contact. OFF indicates that the relay common is in contact with the normally-closed (NC) contact. Relay Isolated input registers The isolated input registers are located at BADR + 1 (Port A) and BADR + 5 (Port B). WRITE No Function READ STATUS Read the status of the isolated inputs. A "1" in the input bit position indicates that a voltage is present at the input. Input # Input filter control registers The input filter control registers are located at BADR1 + 2 (Port A) and BADR1 + 6 (Port B). WRITE Filter Selection 1 = Filter enabled 0 = Filter disabled READ No Function Filter #

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